Oxidative dehydrogenation processes

ABSTRACT

Organic compounds are dehydrogenated to compounds having a higher degree of unsaturation by contacting the feedstock in the vapor phase at an elevated temperature in the presence of an oxygen-containing gas with a calcined catalyst containing a ferrous group metal, e.g., nickel, in combination with phosphorus, at least one Group IIa metal and oxygen. Representative of such conversions is the oxidative dehydrogenation of butane to 1,3-butadiene. The conversion products are valuable compounds particularly useful as intermediates for the preparation of polymeric materials such as synthetic rubbers and the like.

Bertus et al.

[ 1 Jan. 21, 11975 OXIDATIVE DEHYDROGENATION PROCESSES Inventors: Brent J. Bertus; Darrell W. Walker,

both of Bartlesville, Okla.

Assignee: Phillips Petroleum Company, Bartlesville, Okla.

Filed: June 28, 1973 Appl. No.: 374,648

Related US. Application Data Division of Ser. No. 140,973, May 6, 1971, Pat. No. 3,793,225.

US. Cl. 260/680 E, 260/683.3 Int. Cl. C07c 5/18 Field of Search 260/680 E, 683.3

References Cited UNITED STATES PATENTS 7/1960 Alexander et al 260/680 E 8/1966 Christmann 260/680 E 3,642,930 2/1972' Grasselli et al 260/680 E 3,666,687 5/1972 Croce et a1 260/680 E 3,670,042 6/1972 Croce et a1 .1 260/680 E 3,751,512 8/1973 Woskow et al 260/680 E Primary Examiner-Paul M. Coughlan, Jr.

[57] ABSTRACT Organic compounds are dehydrogenated to compounds having a higher degree of unsaturation by contacting the feedstock in the vapor phase at an elevated temperature in the presence of an oxygen-containing gas with a calcined catalyst containing a ferrous group metal, e.g., nickel, in combination with phosphorus, at least one Group Ila metal and oxygen. Representative of such conversions is the oxidative dehydrogenation of butane to 1,3-butadiene. The conversion products are valuable compounds particularly useful as intermediates for the preparation of polymeric materials such as synthetic rubbers and the like.

8 Claims, No Drawings "OXllDATlVE DEHYDROGENATION PROCESSES This application is a divisional application ofcopending application Ser. No. 140,973, filed May 6, l97l, now US. Pat. No. 3,793,225.

The present invention relates to chemical compositions. More particularly, the invention relates to catalyst compositions, their preparation and to catalytic processes employing such compositions, c.g., processes for effecting the dehydrogenation of hydrocarbons.

Thermal catalytic and noncatalytic processes for converting organic compounds to compounds having a higher degree of unsaturation are known. The former are characterized by undesirable side reactions, low order of conversion and yields and poor product selectivity. The catalytic processes are generally characterized by the particular catalytic material employed and the conditions under which the processes are operated, e.g., in the absence or presence of oxygen. While a number of such catalytic processes have attained some measure of commercial success, there is a continuing search to develop catalytic materials for such processes. Preferred as catalysts for such processes are those materials which are more efficient in minimizing side reactions, in improving conversion rates, in improving yields and selectivites to desired end product, and which have a low susceptibility to deactivation, i.e,. are capable of extended periods of operation without regeneration, and can be readily regenerated when necessary. The problem constantly faced by those skilled in the art is the discernment and characterization of the compositions which are highly efficient dehydrogenation catalysts.

A number of catalysts and catalyst systems which include halogens or halogen-releasing compounds have been disclosed. These exhibit many disadvantages in regard to equipment corrosion as well as the expense of continuously feeding, recovering and recycling the relatively expensive halogen materials. Halogen-free catalysts are the most desirable for use in dehydrogenation processes.

The present invention provides a novel catalyst and a novel process for the conversion of organic feedstocks to products having a greater degree of unsaturation and which have the same or lower number of carbon atoms as in the feed According to this invention, an organic feedstock can be converted to products having a greater degree of unsaturation by contacting said feedstock under dehydrogenation conditions in the vapor phase in the presence of molecular oxygen with a calcined catalytic material comprising phosphorus in association with at least one of the metals nickel, cobalt or iron in combination with at least one Group Ila compound. The invention process is particularly applicable to the conversion of hydrocarbons. Thus, paraffmic hydrocarbons can be converted in good yields to diolefins and/or monoolefins, and monoolefins can be converted to diolefins. The invention is particularly applicable for the production of diolefins from paraffins and particularly useful results are obtained by the dehydrogenation of butane to 1,3-butadiene.

The hydrocarbon feedstocks which are applicable for the oxidative dehydrogenation processes of the present invention comprise dehydrogenatable aliphatic hydrocarbons having from 2 to about 12 carbon atoms per molecule and at least one grouping, i.e., at least two adjacent carbon atoms'having at least one hydrogen on each carbon. These can be branched or unbranched, cyclic or acyclic, and include paraflins and monoolefins, but paraffins are presently preferred. Particularly preferred as feed materials are dehydrogenatable aliphatic hydrocarbons having from about 4 to about 8 carbon atoms per molecule. The conversion of butane has been found particularly advantageous by the processes of the invention. Some specific examples of other feeds include ethane, propane, isobutane, pentane, cyclopentane, methylbutanes, hexane, 2-methylhexane, octane, 2,4- dimethyloctane, butene-2, 2-methylbutene-l, hexene- 2, octene-l, 3-methylnonene-4, and the like, including mixtures of such compounds.

The novel catalysts of the present invention comprise phosphorus and at least one Group lla metal in association with at least one metal selected from the group consisting of nickel, cobalt or iron. For convenience, the metal group consisting of nickel, cobalt or iron will be referred to as the ferrous group metals, or simply the ferrous metals. These elements are not in the elemental state but are combined with sufficient oxygen to form one or more neutral compounds, for example, mixtures of nickel oxide, nickel phosphate, phosphorus oxide, magnesium phosphate, magnesium oxide, iron oxide, cobalt phosphate, and the like.

As noted, the catalysts of this invention comprise a catalytically active association of phosphorus, at least one ferrous metal component, and at least one Group Ila metal component, in combination with sufficient oxygen to satisfy the valence requirements of the several individual components Thus, the amount of oxygen will be 100 percent less the combined percentage of the several individual components, i.e., the sum of phosphorus, ferrous metal and Group Ila components. In forming the catalysts of the invention, nickel is preferred for those embodiments containing a single ferrous metal component; in those embodiments containing a mixture of ferrous metal components, combinations of nickel-cobalt and nickel-iron are preferred.

Generally, the phosphorus component will be present in an amount such as to provide a phosphorus to ferrous metal atomic ratio in the range of 0.0l0.65:l, preferably 0.1-0.4:1. The Group lla component will generally be present in an amount sufficient to provide an atomic ratio of Group Ila component to ferrous metal component of at least 0.l:l. Preferentially, the amount of Group lla component is such as to provide an atomic ratio of Group Ila to ferrous metal in the range of O.53:l, with an atomic ratio of l2:l being particularly preferred. Of the Group lla materials, magnesium is presently preferred although beryllium, calcium, strontium, and barium can also be used.

Optionally, the above catalyst components can be associated with a catalytic support material. Presently preferred support materials are selected from the group consisting of silica, alumina, boria, titania, zirconia or silica-alumina, although other conventional support materials can also be used. The support material, when used, will comprise from about 10 to about weight percent of the total catalyst composite, including support material.

The above-described catalyst compositions can be, optionally, further associated with a catalyst-modifying quantity of other metals or metal oxides which are effective in improving activity, selectivity, or stability of the catalyst. For example, the catalyst can contain minor amounts of at least one Group la material. Additional adjuvants which can be used as modifiers for the catalysts of this invention are chromium, vanadium. molybdenum, ruthenium. rhodium. iridium, platinum, palladium and osmium. These adjuvants. when used, are generally present in minor amounts. for example, in the range of 0.05- weight percent, preferably 0. l5 weight percent, based on the weight of the abovedescribed catalyst compositions.

The catalysts of the present invention can be prepared by any suitable method. Conventional methods such as coprecipitation, impregnation, or dry mixing can be used. In general, any method can be used which will provide a composition containing the abovedescribed elements in the above-described proportions and which will have a catalytic surface area of at least one square meter per gram.

Thus, a phosphorus compound, a ferrous metal compound and a Group lla compound are combined in any suitable way. Substantially any phosphorus compound, ferrous metal compound and Group lla metal compound can be employed in the catalyst composition so long as none of the compounds are deleterious to the final dehydrogenation catalyst and so long as essentially all of the elements in the compounds used, other than the phosphorus, ferrous metal, Group lla cornpound and oxygen, and other than adjuvant elements which contribute to the effectiveness of the catalyst, are removed from the final catalyst by prior washing or by volatilization.

It has been found that, in some instances, minor amounts of still other elements can be tolerated in the catalyst. For example, when magnesium is incorporated into the catalyst by way of the magnesium sulfate compound, minor amounts of residual sulfur can be found in the finished catalyst, and the catalyst can still be effective. On the other hand, halogen residues are generally undesirable in such catalysts. Therefore, when halide compounds are used in the preparation of the catalyst. it is generally advisable to substantially remove the halogen residue such by sufficient washing at an appropriate point in the preparation procedure.

Suitable phosphorus compounds include phosphoric acid, phosphorus oxides, ammonium phosphate, alkali metal phosphates, alkaline earth phosphates, and the like, including mixtures thereof.

Similarly, suitable ferrous metal compounds can be used. These can include both organic or inorganic compounds. Some examples of these are nickel oxide, nickel acetylacetonate, nickel nitrate, nickel acetate, nickel sulfate, nickel chloride, and the like, including mixtures thereof. Corresponding compounds of cobalt and iron can also be used.

Similarly, examples of catalyst-modifying materials comprising one or more alkali metal compounds can include lithium nitrate, sodium carbonate, potassium chloride, rubidium acetate, cesium nitrate, sodium phosphate, and the like, including mixtures therof.

Suitable Group lla metal compounds which can be used in forming the catalyst of this invention include magnesium sulfate, magnesium carbonate, calcium carbonate, magnesium bromide, calcium chloride, strontium tartrate, barium hydroxide, and the like, including mixtures thereof.

A convenient method of preparation is to coprecipitatc suitable catalyst-forming compounds from aqueous solutions followed by conventional aging, washing. drying, calcining, pelletizing, and the like. To these compositions, either in the wet gel. dry gel or even calcined states, can be mixed or added by impregnation other beneficial metals or even additional amounts of suitable phosphorus or ferrous metal compounds.

When a catalyst support is used, it can conveniently be introduced during the coprecipitation stage of the catalyst preparation. Alternatively, a solid catalyst support, generally in the finished form of a pellet, sphere. or particle, can be impregnated with solutions of the phosphorus compound, a suitable ferrous metal compound and a suitable Group lla compound. The impregnated solid can then be dried and calcined. When other catalyst-modifying agents are used, they can be introduced into the catalyst either before, during or after the phosphorus, Group lla and the ferrous metal compounds have been associated with the support.

Whichever catalyst preparation technique is used, the catalyst is activated prior to contact with the feed hydrocarbon by a calcination step. Thus, the finished catalyst is calcined in an oxygen-containing gas such as air at a temperature in the range of from about 900 to about l500 F. for a time in the range of about I to about 24 hours, or until the catalyst is active for carrying out the oxidative dehydrogenation step.

The hydrocarbon feedstocks can be dehydrogenated according to the processes in the catalyst ofthe present invention at temperatures in the range of from about 800 to about l300 F., preferably from about 950 to about ll00 F., at any convenient pressure such as from 7 to about 250 psia; and at a hydrocarbonzoxygen ratio from about l:().5 to about I24. The presence of steam is frequently beneficial and a steamzhydrocarbon ratio up to about 50:l can be used. The hydrocarbon feed rate will generally be in the range of about 50 to about [200 GHSV. The fixed catalyst bed is the preferred mode of contact, but other modes, such as a fluidized bed, can also be used.

The dehydrogenation processes of this invention are ordinarily carried out by forming a mixture, preferably preheated, of hydrocarbon feed, the oxygen-containing gas, and the steam (when used) and passing this mixture over the catalyst at the selected temperature. The effluent from the reaction zone is subjected to any suitable separation method to isolate and recover the desired products. Unconverted feeds or partially converted material can be recycled.

Generally, at least trace amounts of oxygenated products are also formed in these reactions. For example, compounds such as furan, acetaldehyde, furfural and acetic acid can be obtained. In some instances, butadiene can be formed as a by-product of the oxidative dehydrogenation of isopentane to isoprene.

The catalyst can operate for long periods without regeneration. However, if and when regeneration is required, this can be accomplished by simply halting the flow of feed hydrocarbons. Contact with the catalyst to the air and steam can be maintained at the elevated temperature until sufficient activity is restored.

The invention can be illustrated by the following expamples.

EXAMPLE l Preparation of Catalysts Catalyst A: Sufficient quantities ofnickel oxide, magnesium sulfate and phosphoric acid to produce a Ni/Mg/P/O composition having a Ni:Mg:P ratio of l.0:O.24:0.l3 were blended by dry mixing. The resulting mixture was slurried with water, dried at 300 F. for 3 hours and calcined at l2()0 F. for about 16 hours. The calcined mixture was crushed and screened to a -30 mesh screen size.

Catalyst B: The procedure of Catalyst A was used to produce a Ni/Mg/P/O catalyst having a nickel2magnesium:phosphorus atomic ratio of l:l:0.l 1.

Catalysts C, D, E and F: Separate portions of Catalyst B were contacted with solutions ofa sufficient quantity of cobalt nitrate, ammonium vanadate, chromic acid and platinum chloride, respectively, to further promote the Ni/Mg/P/O catalyst by incorporating 5 percent by weight cobalt, 5 percent by weight vanadium, 1 percent by weight chromium, and 0.5 percent by weight platinum, respectively, based on the Ni/Mg/P/O catalyst. The impregnated catalysts were again calcined at l000 F. for about 12 hours.

EXAMPLE ll Oxidative Dehydrogenation of Butane The above-described catalysts were charged to a fixed bed reactor and used in several runs in which butane was dehydrogenated in the presence of air and steam. Run conditions with results ofthese several runs are reported in the following Table I. For purposes of comparison, a catalyst similar to the invention Ni/Mg/- P/O catalyst, except that it contained no magnesium, was also tested for butane oxidative dehydrogenation. This comparison Ni/P/O catalyst is designated Catalyst G in the table.

TABLE I Oxidative Dehgdrogenation of Butane Atomic Eat in Adjuvant, Steam: Hydro- Air Tem 11 Catalggt Ni:l-lg:P carbon Ratio GHSV G'lSV F.

1 A 1 0,200.13 10:1 250 900 2 "i 1 0,250.13 10:1 50 250 1050 3 A 1 0.2150,].3 10:1 50 250 1100 L B 1 1:0.11 10:1 5C0 2.650 1100 1 0 Co (5 s) 10:1 500 2050 1000 a u v (5 a) 10:1 500 2550 1000 E Cr (1 g) 10:1 500 2050 1000 1 F Pt .5 1011 5 0 2650 1000 G 10:1 300 1500 1100 (:1) To butadienes and butenes. Modivity is a modified hydrocarbons, carbon oxides and unconverted feed.

as used herein, conversion/yield are re orted on same basis as modivity.

maintaining such conversion and modivity over a long period of time on-stream.

While certain embodiments of the invention have been described for illustrative purposes, the invention is not limited thereto. Various other modifications or embodiments of the invention will be apparent to those skilled in the art in view of this disclosure. Such modifications or embodiments are within the spirit and scope of the disclosure.

We claim:

1. A process for the de h y d o g e n gtign of a dehydrogenatable aliphatic hydrocarb o n feedstock having from 4 to 8 carbon atoms which comprises contacting said feedstock in the vapor phase under dehydrogenation conditions in the presence'of molecular oxygen and in the absence of halogen with a catalyst cori sTsTiiig of nickel, at least one Group lla metal, phosphorus and combined oxygen wherein the llazNi atomic ratio is in the range of 0.5-3:1 and the PM atomic ratio is in the range of 0.0l0.65:1 and optionally from 0.5 to 10 weight percent of an adjuvant selected from the group consisting of Group la metals, chromium, vanadium, molybdenum, ruthenium, rhodium, iridium, platinum, palladium and osmium.

2. The process of claim 1 wherein said Group Ila metal is magnesium.

3. The process of claim 1 wherein said catalyst contains from 0.05 to 10 weight percent of catalyst of an adjuvant selected from the group consisting of Group la metals, chromium, vanadium, molybdenum, ruthenium, rhodium, iridium, platinum, palladium, and osmium.

t. The process of claim 2 wherein said feedstock is teue...

5. A process for the dehydrogenation of a dehydrogenatable aliphatic hydrocarbon feedstock having from 4 to 8 carbon atoms which comprises contacting Hodziv- Yields Time, Conv it eutsnes a Hrs. 2 Butadiene Pu -sine 'it liene 1 25. 53.9 6.0 11.0 1 3617 111.9 12.0 3.0 5.1. 1 1.1.0 3 .1 11.0 1.,2 1a.? 2 37.0 66.1, 21.4 a 38.1 67.0 25.5 s 37.9 67.3 73.5 37.9 66. 95.? 10 17.9 66.5 ?.2 12 36.L 66.5 11. 1;.s 21,.2 12 32.2 60.0 0.1 11.1 20.4 12 33.0 65.5 10.1 11.0 11 12 16.3 31,.6 1,.3 1.3 a.. 12 26.8 7231 8.0 11.5 13.5 2 .9 52.2 m .0 n.

selectivity based on analysis of yes phase irr-dnct for cnnver-ler! 6. The process of claim wherein said Group [la la metals, chromium, vanadium, molybdenum. ruthemctal is magnesium. nium. rhodium, iridium, platinum. palladium. and os- 7. The process of claim 5 wherein said catalyst conmium. tains from 0.05 to 10 weight percent of catalyst of an The process of claim 6 wherein said feedstock is adjuvant selected from the group consisting of Group 5 butane.

UNITED STATES PATENT OFFICE CERTIFICATE O'FCORRECHQN PATENT NO. 5 3,862,255 r Y r DATED January 21, l975 INVENTOR($) Brent J-. Bertus et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 1, column '6, line 20, 0.5 should be 005 Signed and sealed this 20th day of May 1975..

(SEAL) v Attest:

. C. MARSHALL DANN RUTH C. MASON Commissioner of Patents r and Trademarks Attesting Officer 

1. A PROCESS FOR THE DEHYDROGENATION OF A DEHYDROGENATABLE ALIPHATIC HYDROCARBON FEEDSTOCK HAVING FROM 4 TO 8 CARBON ATOMS WHICH COMPRISES CONTACTING SAID FEEDSTOCK IN THE VAPOR PHASE UNDER DEHYDROGENATION CONDITIONS IN THE PRESENCE OF MOLECULAR OXYGEN AND IN THE ABSENCE OF HALOGEN WITH A CATALYST CONSISTING OF NICKEL, AT LEAST ONE GROUP 11A METAL, PHOSPHOROUS AND COMBINED OXYGEN WHEREIN THE 11A:NI ATOMIC RATIO IS IN THE RANGE OF 0.5-3:1 AND THE P:NI ATOMIC RATIO IS IN THE RANGE OF 0.01-0.65:1 AND OPTIONALLY FROM 0.5 TO 10 WEIGHT PERCENT OF AN ADJUVANT SELECTED FROM THE GROUP CONSISTING OF GROUP IA METALS, CHROMIUM, VANADIUM, MOLYBEDENUM, RUTHENIUM, RHODIUM, PLATINUM, PALLADIUM AND OSMIUM.
 2. The process of claim 1 wherein said Group IIa metal is magnesium.
 3. The process of claim 1 wherein said catalyst contains from 0.05 to 10 weight percent of catalyst of an adjuvant selected from the group consisting of Group Ia metals, chromium, vanadium, molybdenum, ruthenium, rhodium, iridium, platinum, palladium, and osmium.
 4. The process of claim 2 wherein said feedstock is butane.
 5. A PROCESS FOR THE DEHYDROGENATION OF A DEHYDROGENATABLE ALIPHATIC HYDROCARBON FEEDSTOCK HAVING FROM 4 TO 8 CARBON ATOMS WHICH COMPRISES CONTACTING SAID FEEDSTOCK IN THE VAPOR PHASE UNDER DEHYDROGENATION CONDITIONS IN THE PRESENCE OF MOLECULAR OXYGEN AND IN THE ABSENCE OF HALOGEN WITH A CATALYST CONSISTING OF COBALT, AT LEAST ONE GROUP 11A METAL, PHOSPHORUS AND COMBINED OXYGEN WHEREIN THE 11A:CO ATOMIC RATIO IS IN THE RANGE OF 0.5-3:1 AND THE P:CO ATOMATIC RATIO IS IN THE RANGE OF 0.01-0.65:1 AND OPTIONALLY FROM 0.05 TO 10 WEIGHT PERCENT OF AN ADJUVANT SELECTED FROM THE GROUP CONSISTING OF GROUP 1A METALS, CHROMIUM, VANADIUM, MOLYBDENUM, RUTHENIUM, RHODIUM, RIDIUM, PLATINUM, PALLADIUM AND OSMINUM.
 6. The process of claim 5 wherein said Group IIa metal is magnesium.
 7. The process of claim 5 wherein said catalyst contains from 0.05 to 10 weight percent of catalyst of an adjuvant selected from the group consisting of Group Ia metals, chromium, vanadium, molybdenum, ruthenium, rhodium, iridium, platinum, palladium, and osmium.
 8. The process of claim 6 wherein said feedstock is butane. 